Here are some hints that you could use in any counter strike. Great for starters:
Always buy a Kevlar + helmet
It can make the difference. Two close grenades can knock you off, but with the Kevlar, you may survive.
A shot on the head from afar can know you off, but with the helmet, you may survive.
So don’t forget it.
Don’t make noise
Close to doors, always remember to press shift to walk instead of run, so that your opponents don’t hear you. And stay alert to hear your opponents foots and attack first.
Knife is lighter
Noticed that rifles makes you run slower because they are heavy. So when you need to run, use always the knife, is lighter and makes you run faster.
Intelligent use of the rifles
Enemies from afar can be hard to knock off with the ak-47 or M4. Don’t let your crosshair grow too much or you will loose your aim. Always stay calm and shot with precision.
Stop only when you must
Shooting while in movement is hard to hit your enemy, especially with a rifle, but staying still makes you a vulnerable target. So move yourself, and stop when you have to shot.
No ammo, no reload
If you run out of ammo in your primary weapon, never reload it right away, or your enemy may take that chance to finish you off. Is better to switch to your pistol and try to knock out your enemy before he knocks out you.
Use the “Q” key.
In a direct combat, the “Q” key from your keyboard can be really helpful. It is just aside your movement keys; its function is to switch the weapon you’re currently using to the previous weapon you were using. So if you run out of ammo in your primary weapon, try using the “Q” key to switch to your pistol in an instant, instead of using the mouse scroll or the number keys.
Your enemy’s weapon
If you just killed an enemy, ran out of ammo, and another enemy appears, don’t reload your weapon right away, is better to retreat, but if you don’t have time, use the weapon that the enemy that you killed dropped. It spears you lot’s of precious time. If your enemy’s weapon is stronger keep it.
If your enemy is far away, look around you and see if there is a rifle nearby, you can use it.
Deactivation kit
When you’re a ct, never, but never go fight without a deactivation kit. They are cheap and they can save your team. Deactivating the bomb without the kit takes to long, but with the deactivation kit, you can deactivate the bomb in only 4 or 5 seconds.
Deactivating the bomb, gives you 3 points extra.
Explore the maps
If you just entered in a new map, and you don’t know it, there are two solutions for you.
Never leave your team, always follow them and at the same time try to memorize the map, so that you aren’t taken by surprise by your enemy. Or you can use the two first rounds to run at will to know better the map.
Time to fight, time to run
If you are alone, and you spot 3 enemy’s, sometimes is better to retreat than to fight. Hide yourself and try to catch them by surprise. Because in a 3 vs 1, you die almost certainly.
Hope this hints were helpful to you.